1. Field of Use
This invention relates generally to intentional distortion of Radio Frequency Identification (RFID) devices, and more particularly to devices for preventing unauthorized electronic retrieval of personal information from identification cards, credit cards, and other RFID equipped cards.
2. Description of Prior Art (Background)
Radio Frequency Identification technologies, commonly referred to as RFID, utilize electronic signals to identify people and objects. In general, a RFID system comprises at least one microchip and an antenna, together referred to as an RFID transponder or tag, and at least one reader. The antenna enables the chip to electronically transmit identification data to the reader. The reader receives and converts the radio waves into digital information for further processing.
RFID systems are used in numerous industries, the most common being use of RFID systems for asset tracking purposes. Active RFID tags have their own transmitter and power source and are therefore used for tracking larger objects across greater distances. Passive RFID tags do not have either a power source or an antenna. Instead they simply reflect radio waves back to a reader associated with the transmission a of an electronic signal. Passive tags are therefore more limited in range. Examples of passive tag systems include tollbooth applications enabling a transponder on a vehicle to reflect a signal to a reader in the tollbooth and inventory tracking systems in retail stores that track inventory movement within the store and prevent theft of items from the store.
More recently RFID systems have been implemented into touchless express pay systems whereby payment can be made by simply waving a credit card or key fob in front of a reader. Although highly convenient, express pay systems incorporate the inherent danger that the associated account will be charged by accident or possibly charged without the owner's knowledge. Indeed, theft of credit or debit card information and identification has become rampant worldwide. Governments, companies, and consumers spend millions of dollars each year to prevent and pursue such thefts.
Nevertheless, recent developments in security technology still do not fully address potential security breaches of an RFID system; such as when an unauthorized RFID interrogation or reading device attempts to extract the RFID information, especially when a user or possessor of an RFID device is unsuspecting or not cognizant that the RFID device is being interrogated. Others have attempted solutions at blocking RFID devices to enhance privacy.
Prior art solutions typically involve a shielded wallet or bill-fold comprising a textile material having electromagnetic shielding incorporated therein. In other words, prior art solutions attempt to shield or block electromagnetic signals from reaching the RFID device. This approach often leads to bulky shielding solutions, such as, for example, cases made of aluminum. In addition, while aluminum is often used as electromagnetic shielding of an electric field it can fail to block a magnetic field. Other prior art solutions disclose lengths of electromagnetic shielding for electric fields but also fail to disclose layers of electromagnetic shielding wherein each layer of the electromagnetic field is adapted to block different types of electromagnetic fields due to different types of RFID data transfer, e.g., electric fields associated with RFID backscatter techniques and magnetic fields associated with RFID magnetic dipole antennas. In addition, prior art textile or fabric type shields are generally designed to block electromagnetic frequencies in the high megahertz (MHz) to gigahertz (GHz) range. However, mainstream RFID frequency ranges are on the order of below 150 kilohertz (KHz) for magnetic inductive coupling to about 15 MHz for inductive coupling and backscatter techniques.
Still other complex prior art solutions disclose an RFID card designed to radiate an interference pattern sufficient to disrupt or interfere with the data transmission of the RFID being interrogated. These solutions, aside from being expensive, require that the interfering RFID card radiate a pattern of sufficient strength and signal similarity with the interrogated RFID card in order to disrupt or interfere with the signal radiated by the interrogated RFID card. However, these types of solutions are comparatively expensive and require complex micro-circuitry. Moreover, each RFID card, or groups of RFID cards, requiring protection may need a separate interfering RFID matched to its specific type of data transmission. For example, a RFID card using electromagnetic backscatter techniques would need interfering RFID using similar techniques. Likewise, a RFID card using magnetic dipole antenna would require in interfering RFID card using similar magnetic dipole antenna techniques. It will be appreciated that this approach would be very cumbersome for the user to carry extra interfering RFID cards, in addition to the ones the user typically carries. It will also be appreciated that the user would likely be confused which interfering RFID card goes with which RFID card to be protected; particularly since the data communication type of RFID card, e.g., magnetic dipole or electromagnetic backscatter, is not readily apparent.
Shielding against low-frequency magnetic fields is, comparatively, not as easy as shielding against electric fields. The effectiveness of magnetic shielding depends on the type of material—its permeability, its thickness, and the frequencies involved. Due to its high relative permeability, steel is much more effective than aluminum and copper as a shield for low-frequency (roughly below 100 kHz) magnetic fields. At higher frequencies, however, aluminum and copper can be used as well. However, the magnetic shielding properties of these metals are quite ineffective at low frequencies. In general, the magnetic shielding provided by non-magnetic conductor depends upon random eddy currents induced in the non-magnetic conductor by the magnetic reader field and the subsequent random counter magnetic fields opposing the magnetic reader field. Better magnetic shields such as Mu-metal can be found for low-frequency magnetic shielding; but, Mu-metal is very fragile, relies on thickness or depth for its magnetic shielding; and can have severe degradation of its permeability, and hence, degradation of its effectiveness as a magnetic shield by mechanical shocks. Consequently, to be effective, Mu-metal solutions require bulky, difficult to handle, Mu-metal shielding.